Scientists peering back to the oldest light in the universe
have new evidence for what happened within its first
trillionth of a second, when the universe suddenly grew
from submicroscopic to astronomical size in far less than a
wink of the eye.

Using new data from a NASA satellite, scientists have the
best evidence yet to support this scenario, known as
"inflation." The evidence, from the
Wilkinson Microwave
Anisotropy Probe (WMAP) satellite, was gathered during
three years of continuous observations of remnant afterglow
light — cosmic background radiation that lingers,
much cooled, from the universe's energetic beginnings 13.7
billion years ago.

In 2003, NASA announced that the WMAP satellite had
produced a detailed picture of the infant universe by
measuring fluctuations in temperature of the afterglow
— answering many longstanding questions about the
universe's age, composition and development. The WMAP team
has built upon those results with a new measurement of the
faint glare from the afterglow to obtain clues about the
universe's first moments, when the seeds were sown for the
formation of the first stars 400 million years later.

"It amazes me that we can say anything about what
transpired within the first trillionth of a second of the
universe, but we can," said
Charles L. Bennett(pictured at right), WMAP
principal investigator and a professor in the
Henry A. Rowland
Department of Physics and Astronomy at The Johns
Hopkins University. "We have never before been able to
understand the infant universe with such precision. It
appears that the infant universe had the kind of growth
spurt that would alarm any mom or dad."

The newly detected pattern, or polarization signal, in the
glare of the afterglow is the weakest cosmological signal
ever detected — less than a hundredth of the strength
of the temperature signal reported three years ago.
"This is brand new territory," said Princeton University
physicist Lyman Page, a WMAP team member. "We are
quantifying the cosmos in a different way to open up a new
window for understanding the universe in its earliest
times."

Comparing the brightness of broad features to compact
features in the afterglow light (like comparing the heights
of short-distance ripples versus long-distance waves on a
lake) helps tell the story of the infant universe. One
long-held prediction was that the brightness would be the
same for features of all sizes. In contrast, the simplest
versions of inflation predict that the relative brightness
decreases as the features get smaller. WMAP data are new
evidence for the inflation prediction.

The new WMAP data, combined with other cosmology data, also
support established theories on what has happened to matter
and energy over the past 13.7 billion years since its
inflation, according to the WMAP researchers. The result is
a tightly constrained and consistent picture of how our
universe grew from microscopic quantum fluctuations to
enable the formation of stars, planets and life.

According to this picture, researchers say that only 4
percent of the universe is ordinary familiar atoms; another
22 percent is an as-yet unidentified dark matter, and 74
percent is a mysterious dark energy. That dark energy is
now causing another growth spurt for the universe,
fortunately, they say, more gentle than the one 13.7
billion years ago.

WMAP was launched on June 30, 2001, and is now a million
miles from Earth in the direction opposite the sun. It is
able to track temperature fluctuations at levels finer than
a millionth of a degree.

The WMAP team includes researchers at the Goddard Space
Flight Center in Greenbelt, Md.; The Johns Hopkins
University; Princeton University; the Canadian Institute of
Theoretical Astrophysics in Toronto; the University of
Texas at Austin; Cornell University; the University of
Chicago; Brown University in Providence, R.I.; the
University of British Columbia; the University of
Pennsylvania; and the University of California, Los
Angeles.

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